linux – 关于INADDR_ANY的问题

The constant INADDR_ANY is the so-called IPv4 wildcard address. The
wildcard IP address is useful for applications that bind Internet
domain sockets on multihomed hosts. If an application on a multihomed
host binds a socket to just one of its host’s IP addresses,then that
socket can receive only UDP datagrams or TCP connection requests sent
to that IP address. However,we normally want an application on a
multihomed host to be able to receive datagrams or connection requests
that specify any of the host’s IP addresses,and binding the socket to
the wildcard IP address makes this possible.

struct sockaddr_in server_address;
int server_sockfd = socket(AF_INET,SOCK_STREAM,0);
memset(&server_address,sizeof(struct sockaddr_in));
server_address.sin_family = AF_INET;
server_address.sin_addr.s_addr = htonl(INADDR_ANY); // here is my quesion
server_address.sin_port = htons(9734);

bind(server_sockfd,(struct sockaddr*)&server_address,sizeof(server_address));

问题>

如果我们将套接字绑定到特定的IP地址,则套接字只能接收发送到该IP地址的UPD / TCP请求.

正如我在上面的代码中所示,现在套接字server_sockfd与INADDR_ANY绑定.
我只是感到困惑,如果套接字可以在互联网上接收任何请求,它如何仍然可以正常工作b / c.如果套接字响应每个人,互联网上有大量的UDP / TCP请求,
,它怎么还能运作？

//更新客户端代码//

int
main(int argc,char *argv[])
{
    struct sockaddr_in6 svaddr;
    int sfd,j;
    size_t msgLen;
    ssize_t numBytes;
    char resp[BUF_SIZE];

    if (argc < 3 || strcmp(argv[1],"--help") == 0)
        usageErr("%s host-address msg...n",argv[0]);

    /* Create a datagram socket; send to an address in the IPv6 somain */

    sfd = socket(AF_INET6,SOCK_DGRAM,0);      /* Create client socket */
    if (sfd == -1)
        errExit("socket");

    memset(&svaddr,sizeof(struct sockaddr_in6));
    svaddr.sin6_family = AF_INET6;
    svaddr.sin6_port = htons(PORT_NUM);
    if (inet_pton(AF_INET6,argv[1],&svaddr.sin6_addr) <= 0)
        fatal("inet_pton failed for address '%s'",argv[1]);

    /* Send messages to server; echo responses on stdout */

    for (j = 2; j < argc; j++) {
        msgLen = strlen(argv[j]);
        if (sendto(sfd,argv[j],msgLen,(struct sockaddr *) &svaddr,sizeof(struct sockaddr_in6)) != msgLen)
            fatal("sendto");

        numBytes = recvfrom(sfd,resp,BUF_SIZE,NULL,NULL);
        if (numBytes == -1)
            errExit("recvfrom");

        printf("Response %d: %.*sn",j - 1,(int) numBytes,resp);
    }

    exit(EXIT_SUCCESS);
}

//为服务器端代码更新

int
main(int argc,char *argv[])
{
    struct sockaddr_in6 svaddr,claddr;
    int sfd,j;
    ssize_t numBytes;
    socklen_t len;
    char buf[BUF_SIZE];
    char claddrStr[INET6_ADDRSTRLEN];

    /* Create a datagram socket bound to an address in the IPv6 somain */

    sfd = socket(AF_INET6,0);
    if (sfd == -1)
        errExit("socket");

    memset(&svaddr,sizeof(struct sockaddr_in6));
    svaddr.sin6_family = AF_INET6;
    svaddr.sin6_addr = in6addr_any;                     /* Wildcard address */
    svaddr.sin6_port = htons(PORT_NUM);

    if (bind(sfd,sizeof(struct sockaddr_in6)) == -1)
        errExit("bind");

    /* Receive messages,convert to uppercase,and return to client */

    for (;;) {
        len = sizeof(struct sockaddr_in6);
        numBytes = recvfrom(sfd,buf,(struct sockaddr *) &claddr,&len);
        if (numBytes == -1)
            errExit("recvfrom");

        /* Display address of client that sent the message */

        if (inet_ntop(AF_INET6,&claddr.sin6_addr,claddrStr,INET6_ADDRSTRLEN) == NULL)
            printf("Couldn't convert client address to stringn");
        else
            printf("Server received %ld bytes from (%s,%u)n",(long) numBytes,ntohs(claddr.sin6_port));

        for (j = 0; j < numBytes; j++)
            buf[j] = toupper((unsigned char) buf[j]);

        if (sendto(sfd,numBytes,len) !=
                numBytes)
            fatal("sendto");
    }
}

//更新了如何运行此服务器/客户端程序.

$./server_program &
[1] 31047
$./client_program ::1 ciao // Send to server on local host
Server received 4 bytes from (::1,32770)
Response 1: CIAO